Field of the Invention
The invention relates to a delivery valve device for a refrigerant compressor.
Refrigerant compressors of various types, for example reciprocating or rotary compressors, are known, particularly hermetically sealed motor-driven compressors for domestic or commercial refrigeration and air conditioning. All these compressors have the function of compressing a refrigerant fluid.
The general principle of such compressors is illustrated in FIG. 1, which schematically depicts, in a cylinder, a piston 19, a valve plate 11 and a cylinder head comprising two chambers 16 and 18. The walls of the cylinder, the piston 19 and the valve plate 11 delimit a compression/expansion chamber 15. The valve plate 11 has an intake passage 110, between the compression/expansion chamber 15 and the intake chamber 16, and a delivery passage 111 between the chamber 15 and the delivery chamber 18. An intake valve 12 is positioned on the valve plate 11 and pressed against it. During the intake phase, the valve 12 opens under the effect of the pressure difference between the compression/expansion chamber 15, which increases in volume because of the retreating movement of the piston (here assumed to be of the reciprocating type), and the intake chamber 16. The movement of the intake valve is limited by a stop 17. At the end of the intake phase, the valve 12 closes again against the valve plate, sealing the passage 110 against fluid when compression begins.
A delivery valve 13 is positioned on the valve plate 11 and pressed against it. It is generally built in at one end and free at the other end. During the delivery
Phase, the valve 13 opens under the effect of the pressure difference between the chamber 15, where the fluid is compressed under the effect of the piston 19, and the delivery chamber 18. The movement of the delivery valve 13 is limited by a delivery vave stop 14 against which the valve 13 comes into contact. At the end of the delivery phase, the delivery valve 13 closes again against the valve plate 11, sealing against the reflux of the fluid through the passage 111.
In fact, it is found that the operation of the valves explained herein above is more complicated than that. In particular, the intake and delivery valves generally open several times during a given phase in the cycle and experience a fluttering movement between the valve plate and the stop. This flutter leads to metal-to-metal impact which generates noise and greatly increases the noise level of the compressor, particularly as far as the delivery valve is concerned.
A valve device of this type is described for example in American patent U.S. Pat. No. 5,110,272. Therein can be found all the elements described above. The problem that this device sets out to solve is that of giving the delivery valves sufficient flexibility while at the same time keeping its axial bulk to an acceptable level. This is achieved by providing a L-shaped valve. However, this valve lifts a great way off the valve plate when it opens, and is therefore subject to the flutter described above and to the ensuing disadvantages.
The object of the invention is to appreciably reduce the noise level of the compressor by limiting the impact due to the delivery valve.
The subject of the invention is therefore a delivery valve device which overcomes the drawbacks described herein above by virtue of a modification to the a principle of the valve on the delivery side which consists in keeping the delivery valve in constant contact, at both ends, with the valve plate.
According to the invention, there is therefore provided a delivery valve device for a refrigerant compressor of the type comprising a valve plate pierced with at least one fluid delivery passage, at least one delivery valve closing said passage on the downstream side in the direction of delivery of the fluid, and secured, at one of its ends, to the valve plate by first fixing the means and at least one delivery valve stop, said device being characterized in that said delivery valve is secured, at one of its ends, to the valve plate by first fixing means and is held at its other end, in almost permanent sliding contact with the valve plate by a spring secured to the valve plate by second fixing means.
By virtue of the fact that the valve stressing spring allows it to slide but not to lift off the valve plate, there is no bounce and flutter of the valve, hence reducing the noise level.
Another important advantage of the device according to the invention is the increase in the refrigeration capacity of the compressor, for the same cylinder capacity, through the limiting of the effects of delayed closure of the delivery valve.